Properties of olean-12-ene-3 beta,16 beta,22 alpha,28-tetrol and some derivatives

Reaction of olean-12-ene-3 beta,16 beta,22 alpha,28-tetrol (chichipegenin) (1) with methyl orthoformate gives the 16 beta,22 alpha,28-orthoformate (2). Acetylation of the ortho ester followed by hydrolysis gives the tetrol 3 beta-monoacetate (5). It is shown that intramolecular hydrogen bonding occurs in the tetrol (1) and the 3 beta-monoacetate (5) in non-polar solvents. X-Ray crystallographic data on the tetrol and its tetraacetate (4) are reported. The tetrol, C30H50O4, M 474.72, crystallized in the orthorhombic space group P2(1)2(1)2(1) With a 12.363(6), b 31.888(3), c 6.962(3) Angstrom, V 2745(1) Angstrom(3), D-c(Z = 4) 1.149 g cm(-3), N = N(unique) 2394, N-o 1878 [I > 1.5 sigma(I)], N-var 500; R 0.038, R(w) 0.040. The tetraacetate, C38H58O8, M 642.87, crystallized in the monoclinic space group P2(1), with a 10.603(2), b 16.569(1), c 10.814(1) Angstrom, beta 98.72(1)degrees, V 1877.9(4) Angstrom(3), D-c(Z = 2) 1.137 g cm(-3), N 3090, R(merge) 4.67% for N(unique) 2917, N-o 2663 [I > 2.5 sigma(1)], N-var 414; R 0.053, R(w) 0.050.